Atomicquantumsensors fortes0nggeneralrela0vity? - - PowerPoint PPT Presentation

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atomic quantum sensors for tes0ng general rela0vity
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Atomicquantumsensors fortes0nggeneralrela0vity? - - PowerPoint PPT Presentation

Nov 14, 2022 168 likes •592 views

Atomicquantumsensors fortes0nggeneralrela0vity? W.Ertmer&E.M.Rasel IQ/LUH Topics detec0onandobserva0onofgravita0onal waves,

slide-1
SLIDE 1

Atomic
quantum
sensors

 for
tes0ng
general
rela0vity
?


W.
Ertmer
&
E.M.
Rasel
 IQ/LUH


slide-2
SLIDE 2

Topics


  • detec0on
and
observa0on
of
gravita0onal


waves,


  • test
of
the
Lense‐Thirring
effect,

  • test
of
the
Weak
Equivalence
Principle.

slide-3
SLIDE 3

Atom
interferometer
 configura0on


  • detec0on
and
observa0on
of
gravita0onal


waves:
 
Phase
meter,
accelerometer


  • test
of
the
Lense‐Thirring
effect:



Gyroscope


  • test
of
the
Weak
Equivalence
Principle:



Differen5al
Accelerometer


slide-4
SLIDE 4

Gravita0onal
Waves


slide-5
SLIDE 5
  • Abs.
length
varia0on
δl
increases
with
distance!


  • Free
test
bodies
will
change
their
rela0ve
distance

  • Transversal
waves


δl


Strain
in
Space
Curvature


slide-6
SLIDE 6

6


Audio band 1 Hz – 10 kHz Gravity-gradient wall

  • n the ground
  • Ground‐based
detectors
observe
in
the
audio
band

  • Space
detectors
observe
low
frequencies


Gravita0onal
Wave
Sources



slide-7
SLIDE 7

7


Ad LIGO/Virgo NB

1 10 100 1000 10000

10-25 10-24 10-23 10-22 10-21 10-20 10-19 h(f) [1/sqrt(Hz)] Frequency [Hz]

(a) 3 r

d G

eneration (b) LCG T (c ) adv anc ed LIG O (d) adv anc ed Virgo (e) LIG O (f) Virgo (g) G EO 600

(a) (b) (c) (d) (e) (f) (g)

Credit: M.Punturo

LIGO 2005 Advanced LIGO/Virgo (2014) GEO-HF 2009 Einstein GW Telescope

GWD
today
and
in
future


slide-8
SLIDE 8

8


  • Overall
beam
tube
length
~
30km

  • Underground
loca0on


– 
Reduce
seismic
noise


– 
Reduce
gravity
gradient
noise
 – 
Low
frequency
suspensions


  • Cryogenic

  • Squeezing


  • QND
Readout


The
Third
Genera0on

 The
Einstein
Gravita0onal
Telescope

 E.T.


slide-9
SLIDE 9

Can
atomic
sensors
contribute
?


slide-10
SLIDE 10

Combining
microscopic
and
 macroscopic
test
masses


slide-11
SLIDE 11
slide-12
SLIDE 12

|e〉 〉 |g〉 〉

5me
 S


∼
cos[(φ3
‐
φ2)‐(φ2
‐
φ1)]
 Signal
at
the
output
ports



Drag‐free
sensor


ΔΦ ≈ 2keffhL sin ωGWT

( )

slide-13
SLIDE 13

G
 periodicity


Mirror:
Laboratory
System


Fringe
posi0on


Coherent
Atomic
Beam
Spliier
 Posi0on
Sensi0vity



slide-14
SLIDE 14
slide-15
SLIDE 15

Replacement
of
drag‐free
sensor

 at
lowest
Fourier
frequencies




slide-16
SLIDE 16

Averaging
√T/τ
 Atomic
Temperature
an
issue
and
beam
spliier
velocity
:
T2
 Scaling
factor
 averaging



slide-17
SLIDE 17


GW‐Sensors


Performance
 Noise
limited
sensi5vity


slide-18
SLIDE 18



Need
for
Femto‐g


With
cold
atoms
?


ONERA
(2003)


slide-19
SLIDE 19

Raman
Laser


Minimising
phase
noise
 ‐ Increasing
number
of
atoms
 ‐ Bea0ng
the
shot
noise

 ‐ Environmental
control
→
Space
 ‐ Ultrastable
lasers
(frequency,



intensity)


Increasing
sensi6vity
 ‐ 
large
area


k


Holger
Müller
(Berkeley):

 Large
area
atom
interferometry


2 2 2

) /( ) ( ) ( Ω ∂ ∂ Δ = ΔΩ ϕ ϕ

slide-20
SLIDE 20

Raman
Laser


2 2 2

) /( ) ( ) ( Ω ∂ ∂ Δ = ΔΩ ϕ ϕ

Minimising
phase
noise
 ‐ Increasing
number
of
atoms
 ‐ Bea0ng
the
shot
noise

 ‐ Environmental
control
→
Space
 ‐ Ultrastable
lasers
(frequency,



intensity)
 Increasing
sensi6vity
 ‐ 
large
area
 ‐ 
low
frequency
signal

 
long
interac0on
0mes

 
→
large
atomic
mass
 
→
Space
 ‐ 
ultra
cold
atoms
 ‐ 
Coherence


k


Systema0cs


slide-21
SLIDE 21

Seeking
for

 lowest
temperatures
 Quantum
Maier
 in
Microgravity



slide-22
SLIDE 22

22
 1 m 10 m 100 m

From Fountains to Large Facilities

  • Prototype experiments
  • 10m fountain or drop
  • Atom drop tower
slide-23
SLIDE 23

Recent
results:
Evolu0on
of
the
wave
 func0on



Time-of-flight: 50, 100, 500 and 1000 ms

slide-24
SLIDE 24

Recent
results:
Evolu0on
of
the
wave
 func0on



Evaporation over 1s 8000 - 10 000 atoms T < 10nK delocalised after 1s

  • ver 900 µm

900 µm Time-of-flight: 50, 100, 500 and 1000 ms

slide-25
SLIDE 25

Back‐of‐enevelope
es0mates

 for
atomic
phase
meter


  • S/N
limited
resolu0on:
1
to
10‐2
mrad/√Hz



 

 
 
 
Newtonian
Noise


  • Scale
factor
for
displacements:
1.6
10‐6

  • Photon
recoil,
Mul0plica0on
factor:
10‐100



 

 
 
 
to
be
combined
with
high
S/N


  • Displacement
sensi0vity:
10‐9
‐10‐13
m

  • Length,
Mul0plica0on
Factor:
100‐1000
m


  • T≅ 1‐10
s


10‐13‐10‐16


Strain
sensi0vity


ΔΦ ≈ 2keffhL sin ωGWT

( )

slide-26
SLIDE 26

detec0on
and
observa0on
of
 gravita0onal
waves
on
ground


  • Suspension
„free“
gravita0onal
wave
detector

  • Sensi0vity
iden0cal
to
light
interferometer:



„Phase
meter“


  • Newtonian
Noise
is
fundamental
barrier

  • Combining
sensors
at
different
Fourier


frequencies
(light
and
maier
interferometer)


  • You
need
a
pair
of
detectors
for
signal
correla0on


slide-27
SLIDE 27

detec0on
and
observa0on
of
 gravita0onal
waves
on
ground


Many
„Firsts“
to
be
demonstrated


  • High‐frequency
source
for
ultracold
(BEC)
atoms
(10Hz


rate)


  • Combining
high‐recoil
beam
spliiers
with
high
phase


resolu0on


  • Sub‐mrad
resolu0on
per
shot

  • Novel
microwave
sources
&
ultra
stable
lasers

  • Control
of
systema0c
errors

  • ...

slide-28
SLIDE 28

detec0on
and
observa0on
of
 gravita0onal
waves
in
space


  • Control
of
drag‐free
sensor
at
lowest
Fourier


frequencies




  • Replacement
of
the
drag‐free
sensor
for


measurements
at
lowest
Fourier
frequencies.


slide-29
SLIDE 29

…with
cold
atoms



Towards
the
limits




Accelera5onal
Sensi5vity
with
10
8
ats:

 Microgravity
10‐12
g/√Hz
@
Expansion
Time
3
s
 Rota5onal
Sensi5vity
with
10
8
ats:

 Microgravity:
8⋅10‐12
rad/√Hz
@
Expansion
Time
3
s


slide-30
SLIDE 30

Extended
Time
of
Evolu6on


Rota0onal
Phase
ship
 Accellera0onal
Phase
ship


Iner0al
Quantum
Sensors


Sagnac
Interferometer


Δϕrot = 2mAtom   A ⋅ ∝T 2

 a

 Ω  Ω

Δϕacc = T 2  k ⋅

 a

Benefits
of
µ‐gravity
environment


slide-31
SLIDE 31

Extended
Time
of
Evolu6on


Rota0onal
Phase
ship
 Accellera0onal
Phase
ship


Increase
in
sensi0vity


Δϕrot = 2mAtom   A ⋅ ∝T 2

 Ω

Δϕacc = T 2  k ⋅

 a

Transportable
Cold
Rubidium
Sagnac
 Interferometer
 kT2


slide-32
SLIDE 32

CASI


slide-33
SLIDE 33

CASI


slide-34
SLIDE 34

Coherent
beam
splirng


slide-35
SLIDE 35

MIXER


Coherent
beam
splirng


slide-36
SLIDE 36

Velocity
selec0on


slide-37
SLIDE 37

Rb
Clock


slide-38
SLIDE 38

Rota0on
sensor


10‐8
rad/s√Hz


slide-39
SLIDE 39

Applica0ons:
 ‐ Inves0ga0on
of
the
 Earth‘s
rota0on
 ‐ Geology
 ‐ Star
mo0on
 ‐ Satellite
naviga0on
 ‐ Rela0vis0c
effects
 ‐ …
 Gravity
Probe
B
 VLBI
 
Effects:
 ‐ seismology
 ‐ Tidal
forces
 ‐ Varia0on
of
the
 Earth‘s
rota0on
 ‐ Rela0vis0c
Effects
 Resolu0on:
 10‐8
–
10‐9
rad
in
 24
h
 Resolu0on:
 10‐9
rad
in






 1
year

 ΩE
 10‐4




10‐5




10‐6




10‐7




10‐8




10‐9




10‐10




Resolu0on:
 10‐10
–
10‐11
rad/ s
√Hz‐1
 The
Earth‘s
rota0on:
 ΩE
≈
7,2∙10‐5
rad/s
 Ringlaser



Rota0on
sensing




slide-40
SLIDE 40


Effects:
 ‐ seismology
 ‐ Tidal
forces
 ‐ Varia0on
of
the
 Earth‘s
rota0on
 ‐ Rela0vis0c
Effects
 Resolu0on:
 10‐8
–
10‐9
rad
in
 24
h
 ΩE
 10‐4




10‐5




10‐6




10‐7




10‐8




10‐9




10‐10




The
Earth‘s
rota0on:
 ΩE
≈
7,2∙10‐5
rad/s



Rota0on
sensing




slide-41
SLIDE 41

Perspec0ves


Quantum
sensors


  • New
atom
interferometric


techniques
are
emerging


  • Fundamental
limits
?


GWD:


  • Bringing
free
fall
to
earth

  • Atom‐light
interferometer
is
the


most
realis0c
scenario
 Joint
Ac0ons
needed

 in
order
to
proceed
further
 for
 GAQS

 Gravita0onal
Wave
Atomic
Quantum
 Sensor



slide-42
SLIDE 42

ENOUGH
SPACE

FOR
EXCITING

 EXPERIMENTS